antenna with coils

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photovision

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At one time I had a Radioshack mag mount on a makeshift ground plane mounted at roof level. It worked quite well. Most base scanner antennas do not seem to incorporate the use of coils. Do you think a ground plane or a discone type or the mag mount with the tuned coils would be more efficient for general coverage?

Thanks for the opinions
 

teufler

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Coils comprss the range of the antenna on transmit and receive. Now if the area of the band you desire is close to the portion that the antenna favors, you will nor little difference. Now if I take a mobile dual band antenna and mount it at the same height as my normal antenna, it will not di as good as the overall height will produce a poorer reception. On HF, years ago I worked into Hawaii with as ground mounted 5btv. A friend had a 18-ht hytower so say 60 feet against about 18 feet tall. Reports from Hawaii had me a 1/2 s unit lower, so the longer the antenna was better but not by much. If the stuff you listen to is say 40 miles or less, the coil antenna will not be much different .
 

LtDoc

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That coil in an antenna effectively makes that antenna longer. It will appear to be 'longer/taller' to the radio, closer to the 'right' length, and the radio will be 'happy' with it. Will it do what you want it to do? Beats me, it might.
- 'Doc
 

jackj

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What do you consider "general coverage"? If you are looking for something that will be resonate across 100 to 1000 MHz then no. It won't work as well as a discone over that wide of a range. If you want to cover say 150 - 160 MHz and 450 - 460 MHz with nothing in between then it would be better - if the coil was a trap. The trap is a parallel.tuned circuit, resonate ~455 MHz - it would isolate the UHF portion of the antenna from the rest of it. You would end up with 2 quarter-wave antennas resonate at the frequencies you are interested in.
 

photovision

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The areas I listen to are in the ranges of 46MHz, 155MHz and 460MHz. I was just thinking that because the mobile antenna was "tuned" to those ranges that it might be more efficient than an antenna that was just a wideband type. I guess neither type has any gain so maybe it doesn't really matter.
 
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